Icemaker system with wide range condensing temperatures

ABSTRACT

A refrigeration system having two alternatively actuable condensers operating at different condensing temperatures and pressures includes a compensatory metering arrangement for preventing significant changes of refrigerant fluid flow rate to the system evaporator when the system switches from one condenser to the other. Compensation is effected by changing the size of the metering orifice as necessary to accommodate the different condenser operating pressures. In one embodiment a thermostatic expansion valve is modified to include a damping factor preventing rapid changes in the valve position. Damping is achieved with a liquid-filled damping chamber having a damping diaphragm as one wall secured to the valve actuator rod. Opening of the valve requires the damping diaphragm to compress the liquid which is permitted to leak from the damping chamber at a controlled rate to slow the valve actuation rate. The system has particular utilization in the formation and collection of purified ice pieces from unpurified water and the formation of purified water by the selective melting of ice pieces using rejection heat from one of the alternatively operative condensers. In an alternative system embodiment, electrical heating of the collection bin is employed to melt ice pieces.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 07/494,546 filed Mar. 16, 1990, which is a continuation-in-part ofmy co-pending U.S. patent application Ser. No. 07/437,161 filed Nov. 16,1989, now U.S. Pat. No. 4,941,902, which is a divisional application ofmy prior U.S. patent application Ser. No. 07/278,447, filed Dec. 1,1988, now U.S. Pat. No. 4,897,099.

Other related applications include my co-pending U.S. patentapplications Ser. No. 07/471,884 and Ser. No. 07/471,885, both filedJan. 29, 1990 as continuation-in-part applications of the aforesaidapplication Ser. No. 07/278,447.

The subject matter of all four of the aforesaid applications isexpressly incorporated herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for controllablyvarying the flow rate and pressure of refrigerant fluid delivered to anevaporator in a refrigerant system of the type wherein two condensersoperating at different temperatures and pressures are alternativelyactuated. The invention has particular utility in systems of the typedisclosed in my aforementioned prior patent applications whereinpurified ice pieces are formed from tap water and then selectivelymelted to provide purified water.

In my aforesaid patent applications I disclose systems wherein heat tomelt ice pieces is derived from a condenser employed in the ice-makerrefrigeration cycle. Provision is made to maintain the condensingtemperatures (and, therefore, the condensing pressures) at appropriatelyhigh levels while the condenser rejection heat is employed to melt theice pieces. These high temperatures and pressures serve to maintain anadequate flow of refrigerant fluid through the metering device to theevaporator of the refrigeration system.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method andapparatus for permitting the refrigerant condensing function to occur atrelatively low temperatures in the ice-melting condenser whilemaintaining adequate flow through the refrigerant metering device to theevaporator.

In accordance with the present invention, condensing is permitted atrelatively low temperatures by placing the melting condenser in directcontact with the bottom of the ice piece collection bin. Adequaterefrigerant flow is maintained by utilization of unusually largemetering orifices. The system is adaptable to higher condensingtemperatures, at such time as when ice is not being melted by thecondenser, by automatically decreasing the size of the metering orifice.When a lower condensing temperature is employed, less power is consumedby the refrigerant compressor which is no longer required to pumpagainst the high discharge pressure present with higher condensingtemperatures. In one embodiment of the invention, a wide rangethermostatic expansion valve automatically adapts to the varyingcondensing temperatures to control the metering orifice size. The valveresponds to the temperature of the refrigerant fluid to open and closethe metering orifice accordingly. A damping mechanism is employed in thevalve to limit its actuation rate at the onset of opening and closing toprevent overfeeding of refrigerant fluid to the evaporator immediatelyafter changeover occurs from one condenser to the other.

An alternative ice-melting system is also disclosed wherein anelectrical heater, rather than a second condenser is employed to meltice This embodiment is particularly useful to reduce construction costsfor small capacity systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and still further objects, features and advantages of thepresent invention will become apparent upon consideration of thefollowing detailed description of specific embodiments thereof,especially when taken in conjunction with the accompanying drawingswherein like reference numerals in the various figures are utilized todesignate like components, and wherein:

FIG. 1 is a schematic flow diagram of a system employing one embodimentof the present invention;

FIG. 2 is a schematic flow diagram of a system employing a secondembodiment of the present invention;

FIG. 3 is an elevation view in section of a valve of the presentinvention employed in the embodiment of FIG. 2;

FIG. 4 is a view of a modified portion of the valve of FIG. 3;

FIG. 5 is a schematic flow diagram of still another ice making and icemelting system according to the present invention; and

FIG. 6 is a view of an alternative actuating mechanism for terminatingthe ice melting function in response to accumulated purified waterlevel, which arrangement may be employed in connection with any of thesystem embodiments disclosed herein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to facilitate reference to the disclosure material incorporatedherein from my U.S. Pat. No. 4,897,099 and my other above-describedpatent applications, reference numerals up to and including numeral "86"appearing in the accompanying drawings are chosen to correspond to thosereference numerals employed in the aforesaid patent to designate likeelements. Higher reference numerals appearing in the accompanyingdrawings designate elements not present in the aforesaid patent.

Referring now to FIG. 1 of the accompanying drawings, an ice makerincludes an evaporator tube 2 contacting the dry or control surface of avertical ice-forming plate 3 at multiple spaced locations. For someapplications a plurality of such plates may be employed. Unpurifiedwater discharged as a jet or stream from nozzle 4 flows down along thewet or ice-forming surface of plate 3, whereby ice pieces 5, 6, 7 and 8are formed at the spaced areas corresponding to the locations of contactbetween evaporator tube 2 and plate 3. Refrigerant vapor from evaporator2 flows back to a compressor 9 where it is compressed and then directedto a condensing system described in detail below. Liquid refrigerantreturning from the condensing system is conveyed by liquid line 11 to ametering device 12, typically an expansion valve, and then back toevaporator 2 in a conventional closed circuit refrigeration flow path.Excess water flowing over the growing ice pieces 5, 6, 7 and 8 carriesaway impurities before they can be trapped and then drains into sump 13.Water from sump 13 is drawn by pump 14 and pumped back to nozzle 4 toform a continuous circuit of unpurified water flow.

After a predetermined time has elapsed for ice pieces 5, 6, 7 and 8 togrow to adequate size, a harvest of the ice pieces is initiated. A cam15A of a timer 15 actuates switch points 15B to break an electricalenergizing circuit for pump 14. With pump 14 deactuated, water intransit from pump 14 to nozzle 4, and water flowing over the ice pieces5, 6, 7 and 8, flows back to raise the level in sump 13. As aconsequence, a siphon 16 is activated to dump the remainder of the waterfrom sump 13 to a drain. Timer 15 simultaneously activates switch point15B to deactivate pump 14 and switch point 15C to energize a hot gasvalve 17, thereby allowing hot refrigerant gas to be shunted around thecondenser system and expansion valve 12 to flow directly into evaporator2. The warming effect of this hot gas detaches the ice pieces from plate3, permitting them to fall into ice collection bin 18. Meanwhile, thewater in sump 13 is replenished by tap water from pipe 19 under thecontrol of a float valve 20. After a predetermined ice piece harvestinterval, cam 15A of timer 15 reverses the settings of the switchpoints, de-energizes hot gas valve 17 and reactivates pump 14 so thatice making may be resumed. A repetitive cycle of harvest and ice makingis thus continued until ice collection bin 18 is full, at which time theice pieces come into contact with the ice quantity sensor of bin switch21 which opens to cause compressor 9 to be deactuated. The ice piecesthusly collected, because they are continuously washed by the streamdelivered from nozzle 4 as the pieces are being formed, have a muchhigher purity than that of the original tap water. The ice makingapparatus thus far described is of a type commonly employed and wellknown. Similarly, any other type of ice maker using a recirculating flowof pumped water, and therefore capable of producing a supply of pure icepieces, can be employed in connection with the present invention.

Any ice that melts in bin 18 drains through a pipe 22 having an inlet atthe bottom of the bin. The drained water flows into a bottle 3 or othercontainer resting on a platform 24 hinged at a positionally fixed point25. By "positionally fixed" it is meant that the hinge or pivot point 25is stationary relative to the common cabinet or housing for all of thecomponents described herein. With container 23 full, its weightovercomes the resilient bias force of a balance spring 26 and pullsplatform 24 clockwise (as viewed in the drawing) to swing the platformdownward. This downward movement causes a downward movement of a controllink 27 connected to platform 24 at a connecting pivot 28, the latterbeing movable relative to the common system housing. The opposite end ofcontrol link 27 is attached to a movable pivot point 31 which isattached to rocker arm 29. Downward movement of control link 27 causesclockwise rotation of rocker arm 29 about a positionally fixed pivotpoint 30. This clockwise rotation of rocker arm 29 holds switch 68 open.Electrical current flow to solenoid valves 69 and 70 is thus interruptedso that these valves remain deenergized. With bin switch 2; closed,indicating that the bin is less than full of ice pieces, compressor 9continues to run. Solenoid valve 70 is a normally open valve; therefore,since it is de-energized, valve 70 permits refrigerant fluid, dischargedby compressor 9, to flow to condenser 71. Solenoid valve 69 is anormally closed valve; therefore, since it is de-energized, it isclosed. Condenser 71 may be either air-cooled or water-cooled.Refrigerant liquid flows from condenser 71 to liquid line 11, then tometering device 12 and evaporator 2 in the ice-making functionpreviously described.

If bottle 23 is less than full, its weight is overcome by the resilientbias force of balance spring 26 which pulls platform 24counter-clockwise (as viewed in the drawing) to swing the platformupwardly. Upward movement of the platform causes an upward movement ofcontrol link 27 and a counter-clockwise rotation of rocker arm 29. Inresponse to rotation of rocker arm 29, an override switch 32 closes,thereby bypassing bin switch 21 to permit compressor 9 to run regardlessof the state of the bin switch. Counter-clockwise rotation of rocker arm29 also permits switch 68 to close, thereby completing a circuit toenergize both solenoid valves 60 and 70. When the normally open solenoidvalve 70 is energized, it closes to shut off refrigerant flow tocondenser 71. When the normally closed solenoid valve 69 is energized,it opens to allow flow of compressed refrigerant vapor through pipe 73to condenser coil 102 secured in direct contact with the bottom of icecollection bin 18. Condenser coil 102 acts as a condenser rejecting heatof condensation to melt ice pieces in bin 18. Ice resting at the bottomof bin 18 is thereby melted at a relatively fast rate, and the resultingpurified water is drained by a pipe 22 into container 23.

As ice melts at the bottom of bin 18, the weight of ice pieces in thebin causes more pieces to continually move downwardly to the bin bottom.Meanwhile, the ice-making function continues so that a supply of freshice pieces is collected in the bin. Condensed liquid refrigerant fromcondenser coil 102 flows through pipe 103 and check valve 76 to liquidline 104. Check valve 76 serves to block backflow into condenser coil102 during system shut down. Liquid refrigerant flows in liquid line 104to a second metering device 105, and then back to evaporator 2 in acontinuous refrigeration circuit. Metering device 105 can be anexpansion valve, capillary tube, or other type of throttling device, butit differs from metering device 12 in that its orifice, through whichthe liquid refrigerant passes, must be much larger or, in the case of anexpansion valve, capable of opening to a much larger opening thanprovided in metering device 12. This is required because, when condensercoil 102 is functioning as the system condenser, the high-side pressureis quite low due to a low condensing temperature as compared to thehigher pressure and temperature in condenser 71. Accordingly, with onlythe lower pressure available to propel refrigerant liquid through themetering device, the orifice or opening must be much larger if the sameflow rate to the evaporator is to be maintained. With a typicalrefrigerant fluid such as refrigerant R-502, and with the evaporatoroperating at 20° F. and a low-side pressure of 53 psi, condenser coil102 typically operates at 40° F. and has a high-side pressure of 80 psi.The resulting pressure differential is 27 psi. Condenser 71, on theother hand, typically operates at a 100° F. with a high-side pressure of216 psi, providing a pressure differential of 163 psi.

When water container 23 becomes full, its weight once again overcomesthe bias force of balance spring 26, causing platform 24 to drop (i.e.,pivot clockwise about fixed pivot 25). Control link 27 is thereby pulleddownwardly, rotating rocker arm 29 clockwise to open switch 68 andde-energize solenoid valves 69, 70 and terminating the ice-meltingfunction. Override switch 32 also opens, leaving control of the icemaking function to bin switch 21.

Another embodiment of the invention is illustrated in FIG. 2 of theaccompanying drawings to which reference is now made. The overalloperation of this embodiment is identical to that described for theembodiment illustrated in FIG. 1 except that a single liquid line 11 anda single expansion valve 106 are employed rather than the two meteringdevices 12 and 105 and their associated liquid lines 11 and 104 (FIG.1). An additional check valve 72 is also employed for this embodiment.Expansion valve 106 is capable of controlling a relatively constant flowof refrigerant liquid, regardless of the wide range of pressuredifferentials encountered between the high-side and the low-sidepressures, when condenser coil 102 or condenser 71 are usedalternatively as described above in connection with the embodimentillustrated in FIG. 1. Expansion valve 106 is a wide-range thermostaticexpansion valve of the type described in detail below in relation toFIG. 3.

In the ice-making, non-melting mode of operation of the systemillustrated in FIG. 2, refrigerant vapor from evaporator tube 2 is drawnby compressor 9, compressed and then discharged through valve 70 tocondenser 71. Condensed liquid refrigerant flows through check valve 72,through liquid line 11, and then through expansion valve 106 toevaporator tube 2 in a conventional refrigeration cycle. As describedabove, the differential between the pressures in liquid line 11 andevaporator tube 2 is relatively large when condenser 71 is in operation.When the system is switched to an ice-making, ice-melting mode ofoperation, compressor 9 discharges the compressed vapor through valve 69and pipe 73 to condenser coil 102. Condensed liquid refrigerant flowsthrough pipe 103, check valve 76, liquid line 11 and expansion valve 106to evaporator tube 2. The differential between the pressures in liquidline 11 and evaporator 2 is relatively small when condensing occurs atthe lower temperature of condenser coil 102 (as previously described).Regardless of these disparate pressure differentials, expansion valve106 allows only the appropriate amount of liquid refrigerant to flowinto evaporator tube 2 in these alternative melting and non-meltingmodes of operation. Temperature bulb 107 senses the temperature ofsuction vapor leaving the evaporator 2. Check valves 72 and 76 preventbackflow into condensers 71 and 102, respectively, during theiralternative functions and during system shut down.

Referring now to FIG. 3 of the accompanying drawings, expansion valve106 essentially comprises an oversized thermostatic expansion valve witha damping mechanism for slowing down the rate of opening to: (a) preventoverfeeding of refrigerant fluid until the system is settled in balancedoperation during starting of the system; and (b) prevent hunting. Liquidrefrigerant from liquid line 11 enters inlet port 108 and flows to valveseat 109 which combines with valve head 110 to form the variablemetering orifice of the valve. Power element diaphragm 111 responds tovapor pressure on its upper side from the refrigerant liquid charge intemperature bulb 107. (It is to be noted that use of such terms as"upper side", "underside", "upward", "downward", etc., relates only toorientations in FIG. 3 for simplified understanding and are not to beconstrued as preferred actual orientations of the valve and valvecomponents). Downward mechanical pressure from diaphragm 111 istransferred via collar 112 and push-rods 113 and 114 to valve head 110,tending to move the valve head toward an open valve position. Controlspring 115 provides a bias force in the opposite direction. Outlet port116 connects directly to evaporator tube 2. The vapor pressure presentin the evaporator is present on the underside of diaphragm 111 by virtueof passage 117 connecting the space under diaphragm 111 to the valvebody interior in the region of outlet port 116. The extent of movementof valve head 110 away from valve seat 109, and thus the extent of valveopening or orifice size, depends upon the combined effects of: (1)downward pressure on diaphragm 111 as a function of the temperaturesensed by bulb 107; (2) upward pressure on diaphragm 111 as a functionof evaporator pressure; and (3) upward force from bias spring 115.Adjustable collar 118 has a male screw thread engaging a female screwthread in the body. The tension on control spring 115 can be altered byrotation of collar 118, thus allowing superheat adjustments to be made.

The operation of valve 106 as thus far described is the same as theoperation of a conventional thermostatic expansion valve, except thatthe essential elements of valve 106, such as diaphragm 111, valve seat109, valve head 110 and bias spring 115 are larger than would beemployed in a conventional refrigeration system of correspondingtonnage. This is necessarily so because valve 106, when employed withlow temperature condenser coil 102 (FIG. 2), must permit floW of therequired quantity of liquid refrigerant for that tonnage, but must havea pressure differential between its inlet and outlet that is much lowerthan normal. However, when valve 106 is employed with the normaltemperature condenser 71, its larger sizing causes problems such asoverfeeding of refrigerant fluid when the system is starting up, andhunting when overfeed is followed abruptly by starving, then overfeed,etc., in a repetitive cycle of over-compensation. In order to preventthis, a damping arrangement is provided and includes annular damperdiaphragms 119 and 120. Alternatively, metal bellows may be employedinstead of the diaphragms 119 and 120. Valve head 110 is attached tovalve stem 121 so that any downward movement of the valve head 110,corresponding to opening of the valve orifice, is accompanied bymovement of stem 121. Valve stem 121 is attached to the centers ofdamper diaphragms 119 and 120 by connections that are sealed to holdagainst fluid pressure, such that the movable center sections of thesediaphragms move upward and downward with like movements of valve head110. The stationary outer sections of damper diaphragms 119 and 120 areclamped to the valve body at points 125, 126, 127 and 128.

The valve body includes an annular wall 129 located in the space betweenthe diaphragms 119 and 120 and subdividing the space to form an upperdamping chamber 130 and a lower damping chamber 131. Chambers 130 and131 are filled with a stable liquid such as refrigeration oil. An 0-ring132 seals an aperture provided in wall 129 about stem 121 and permitsthe stem to freely move upward and downward. Transfer of liquid betweenthe upper and lower chambers 130 and 131 is provided by an adjustableorifice 133. Equalizer tube 134 and passage 135 allow the dry sides ofdamper diaphragms 119 and 120 to be maintained at the pressure existingin evaporator 2.

In operation, with the system at rest, and with temperatures andpressures equalized between evaporator tube 2 and temperature bulb 107,the power element diaphragm 111 is relaxed. Accordingly, control spring115 maintains valve head 110 in the closed position. When the compressorbegins operation, pressure is reduced in evaporator tube 2 and,therefore, at the underside of power element diaphragm 111. This causesvalve head 110 to tend to move downward to open the valve. However, suchmovement is resisted by damper diaphragms 119 and 120. Diaphragm 119cannot move freely because of the liquid trapped beneath it, anddiaphragm 120 is held by vapor pressure on its underside and vacuum onits upper side. However, orifice 133 slowly conducts fluid from upperchamber 130 to lower chamber 131, thereby enabling a slow movement ofthe damper diaphragms 119, 120 to provide a slow and controlled openingof the valve. The rate of valve opening can, of course, be adjusted byappropriately setting adjustable orifice 133. Assuming operation withthe low temperature condenser tube 102, as the valve slowly opens, thereis a tendency for the system to become starved for refrigerant. Thisdoes not present a real problem, only a lower than normal evaporatorpressure for a very short time. When valve 106 reaches an orifice sizeconsistent with its superheat setting, pressures and forces equalize andthe valve orifice size remains constant. As the system settles down, andas minor changes occur in operating conditions, the valve adapts itsorifice size to maintain constant superheat in the evaporator, but thesechanges occur slowly so that hunting is avoided. The closing of valve106 is initiated if the temperature at bulb 107 is reduced or if thepressure in evaporator tube 2 is increased. In either case, the dampingprocess is reversed and liquid from the lower chamber 131 is transferredto upper chamber 130. The time required for valve 106 to proceed fromits fully open position to its fully closed position, or from its fullyclosed position to its fully open position, may range from ten secondsto several minutes. With a wide range expansion valve such as valve 106,actual superheating is greater at large orifice openings than at smallorifice openings because of the increase in force applied by bias spring15 as it is compressed. This difference can be minimized by the use of alonger than normal control spring. Such springs have less pressurevariation throughout their movement range.

An alternative improvement of valve 106 is illustrated in FIG. 4 whereinvalve stem 121 is contoured to serve as a metering pin as it movesthrough the aperture in wall 129. 0-ring 132 and adjustable orifice 133are omitted, and the varying clearance between valve stem 121 and theaperture in wall 129 provides the path for liquid transfer betweenchambers 130 and 131. A tapered profile is provided on valve stem 121 sothat the diameter at its bottom section 138 is smaller than the diameterat its top section 139. Small bottom section 138 is aligned with wall129 (as shown in FIG. 4) when valve 106 is in its completely closedposition. The additional clearance at this position results in a rapidinitial rate of opening of valve 106, up to a small orifice size,thereby reducing the tendency of the system to starve for refrigerantduring system start up operation. Then, as valve 106 continues to open,but while still at a relatively small orifice size, larger section 139becomes aligned with wall 129, reducing the clearance and, therefore,the rate of opening. By this method, valve opening and closing rates atthe smaller orifice sizes are relatively fast while opening and closingrates at the large orifice sizes are relatively slow. Alternatively, theprofile on valve stem 121 may be constructed in such form to controlvalve modulation rates in any desired manner. For example, valve stem121 may have a straight parallel profile so that the opening rate isconstant, in which case the clearance between valve stem 121 and wall129 is a simple, non-adjustable substitute for adjustable orifice 133.

An alternative embodiment for expansion valve 106 is a conventionalelectrical expansion valve. Such valves are motorized metering deviceswith refrigerant liquid flow controlled by an electronic microprocessorresponsive to sensors monitoring system conditions. Such devices arewell-known.

If the advantages of a damped expansion valve, such as the embodimentdescribed in relation to FIGS. 3 and 4, are required in an applicationwhere a wide range of pressure differentials are not encountered, thedamping system described herein can be applied to any conventional valveof a size suitable for the tonnage of the system employed. Meteringdevice 12, as illustrated in FIG. 1, is representative of such anapplication.

A simplified ice-melting arrangement of the present invention isillustrated in FIG. 5 to which specific reference is now made.Compressor 9 draws refrigerant vapor from evaporator tube 2 andcompresses and discharges it to condenser 46 which may be eitherair-cooled or water-cooled. Refrigerant liquid flows from condenser 46through a liquid line 11 to metering device 12 and then to evaporatortube 2 in a conventional refrigeration cycle as part of an ice-makingfunction similar to such functions described above in relation to otherembodiments. Ice collection bin 18 contains the ice produced in thisice-making function. In the same manner described in relation to FIG. 1,when water container 23 is less than full, platform 24 is drawn upwardby balance spring 26, thereby pushing upward on control link 27 andcausing rocker arm 29 to rotate counter-clockwise. In this embodiment,the counter-clockwise rotation of rocker arm 29 allows an electricalswitch 141 to close, causing electrical current to flow through switch141 and energize an electrical heating element 142 attached to thebottom of bin 18. Heat produced by element 142 warms the bottom of bin18, thereby melting some of the ice within the bin. Water from themelting ice flows via pipe 22 to container 23. When container 23 isfull, its weight overcomes balance spring 26 causing platform 24 toswing downward, thereby moving control link 27 downward and causingrocker arm 29 to rotate clockwise. This rotation of rocker arm 29 forcesswitch 141 to open, de-energizing heating element 142 18 and terminatingthe ice-melting function. The ice-making function is normally controlledby bin switch 21 as previously described in relation to otherembodiments, and when the ice-melting function is operating, overrideswitch 32 causes the compressor 9 to run continuously so that ice isproduced to replace the ice melted during the ice-melting function. Thisembodiment is less energy efficient than those employing non-electricsources of heat for ice-melting. However, low construction costs canoutweigh the additional operational cost of electrical power forice-melting, particularly with small capacitor systems. Such systemsconsume a minimal amount of energy when only a small amount of purifiedwater is required.

A typical procedure for handling the recovered pure water is to employ aone gallon water bottle 23 (FIG. 1) positioned inside the cabinet onplatform 24. An alternative water storage arrangement (see FIG. 6)employs a water tank 80 mounted permanently inside the cabinet with afloat 82 detecting the level of water within. Float 82 is suspended fromarm 83 secured at one side of fixed pivot point 84, the other side ofwhich is connected to the actuator link 27 via connecting arm 85.Movement of float 82 is a substitute function for movement of platform24 in the embodiment illustrated in FIG. 1.

In addition to the utilization of the present invention for theproduction of purified water, as described above, ice pieces may beremoved from bin 18 for other purposes via bin door 86. Thesearrangements are described in detail in my aforementioned U.S Pat. No.4,897,099.

Having described preferred embodiments of a new and improved ice makersystem with wide range condensing temperatures, constructed inaccordance with the present invention, it is believed that othermodifications, variations and changes will be suggested to those skilledin the art in view of the teachings set forth herein. It is therefore tobe understood that all such variations, modifications and changes arebelieved to fall within the scope of the present invention as defined inthe appended claims.

What is claimed is:
 1. A method for providing a supply of purified iceand a supply of purified liquid water from a source of unpurified liquidwater, said method comprising the steps of:(a) cooling selected areas ofat least one ice-forming surface to a temperature below the freezingtemperature of water by conducting thermal energy to at least oneevaporator passage from said selected areas of said ice-forming surface;(b) directing a water stream of the unpurified liquid water over saidselected areas to form ice at said selected areas while washingimpurities away from the formed ice with said stream; (c) increasing thetemperature at said selected areas at various times to remove said icefrom said ice-forming surface; (d) collecting the ice removed in step(c) in a bin; (e) electrically heating the bottom of said bin atselected times to melt some of the ice collected therein into purifiedliquid water; (f) collecting in a container the purified liquid waterobtained in step (e); wherein said evaporator passage is part of acontinuous refrigerant flow path for refrigerant fluid, said flow pathincluding a compressor, condenser means, metering means and theevaporator passage, and wherein step (a) includes energizing saidcompressor; (g) sensing the amount of collected ice in said bin; (h)sensing the amount of collected liquid water in said container; (i) inresponse to both the amount of said collected ice in said bin exceedinga first predetermined amount, and the amount of said collected purifiedliquid water in said container exceeding a second predetermined amount,de-energizing said compressor; (j) following step (i), re-energizingsaid compressor whenever either or both of the following occurs: (1) theamount of collected ice in said bin falls below the first predeterminedamount; and (2) the amount of collected purified liquid water in saidcontainer falls below the second predetermined amount;and wherein step(e) includes the steps of:(e.1) in response to the amount of collectedpurified liquid in said container being less than said secondpredetermined amount, electrically heating the bottom of said bin; and(e.2) in response to the amount of collected purified liquid in saidcontainer exceeding said second predetermined amount, terminatingelectrical heating of the bottom of said bin.
 2. Apparatus for providingpurified ice and purified liquid water from a source of unpurifiedliquid water, said apparatus comprising:a closed flow path containingrefrigerant fluid and including a compressor, a condenser, evaporatormeans and metering means for delivering the refrigerant fluid to theevaporator means from said condenser means; an ice-forming structurehaving an ice-forming surface and disposed such that said evaporatormeans cools selected areas on said ice-forming surface when liquidrefrigerant flows through said evaporator means; means for flowingunpurified liquid water along said ice-forming surface to form ice atsaid selected areas when said selected areas are being cooled; means forcontrollably increasing the temperature at said selected areas to detachice therefrom; a bin for collecting ice from said selected areas of saidice-forming surface; selectively actuable electrical heater means formelting ice at the bottom of said bin; a container for collecting waterformed by the melting of ice at the bottom of said bin; ice sensor meansfor sensing the amount of ice in said bin and providing a bin-fullindication when the collected ice exceed a predetermined amount, and abin-not-full indication when the collected ice do not exceed saidpredetermined amount; water sensor means for sensing the amount of waterin said container and providing a container-full signal when the watercollected in said container exceeds a specified amount, and acontainer-not-full indication when the water collected in said containerdoes not exceed said specified amount; compressor control meansresponsive to each of said bin-not-full and container-not-fullindications, individually, for actuating said compressor, and responsiveto said bin-full and container-full indications together for deactuatingsaid compressor; and j heater control means responsive to saidcontainer-not-full indication for actuating said electric heater means,and to said container-full indication for deactuating said electricalheater means.
 3. The apparatus according to claim 2 wherein saidelectrical heater means is disposed outside said bin and adjacent thebottom of said bin.
 4. The apparatus according to claim 2 wherein saidwater sensor means comprises an electrical switch having two states, andmeans responsive to the combined weight of said container and watertherein for determining the state of said switch.
 5. The apparatusaccording to claim 2 further comprising:means for collecting unpurifiedwater flowing along said ice-forming surface and not forming part ofsaid ice; and means for recirculating the collected unpurified water toflow along said ice-forming surface.
 6. A method for providing purifiedice and purified liquid water from a source of unpurified liquid waterusing a closed refrigerant flow path containing refrigerant fluid andincluding a compressor, a condensor, an evaporator and a metering devicefor delivering the refrigerant fluid to the evaporator from thecondenser, said method comprising the steps of:cooling selected areas ofan ice-forming surface with said evaporator when liquid refrigerantflows through the evaporator; flowing unpurified liquid water along theice-forming surface to form ice at said multiple selected areas wheneverthe selected areas are being cooled; controllably increasing thetemperature at the selected areas to detach the ice therefrom;collecting in a bin the ice detached from said selected areas of saidice-forming surface; melting ice at the bottom of said bin with aselectively actuable electrical heater; collecting in a container waterformed by the melting of ice at the bottom of said bin; sensing theamount of ice in said bin and providing a bin-full indication when thecollected ice exceed a predetermined amount, and a bin-not-fullindication when the collected ice do not exceed said predeterminedamount; sensing the amount of water in said container and providing acontainer-full indication when the water collected in said containerexceeds a specified amount, and a container not-full indication when thewater collected in said container does not exceed said specified amount;in response to each of said bin-not-full and container-not-fullindications, individually, actuating said compressor; in response tosaid bin-full and container-full indications, together, deactuating saidcompressor; in response to said container-not-full indication, actuatingsaid electrical heater; and in response to said container-fullindication, deactuating said electrical heater.
 7. The method accordingto claim 6 further comprising the step of disposing said electricalheater outside, and adjacent the bottom of, said bin.